Physics
The diagram shows a circuit with the key k open. Calculate:
(i) the resistance of the circuit when the key k is open.
(ii) the current drawn from the cell when the key k is open.
(iii) the resistance of the circuit when the key k is closed.
(iv) the current drawn from the cell when the key k is closed.
Current Electricity
ICSE 2019
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Answer
(i) When k is open, resistance is 5 + 0.5 = 5.5 Ω
(ii) From relation, V = IR
Substituting the values in the formula we get,
Hence, current drawn from the cell when the key k is open = 0.6 A.
(iii) When k is closed, the resistance 2 Ω and 3 Ω are in series, therefore their total resistance is 2 Ω + 3 Ω = 5 Ω . Now since, 5 Ω resistance is in parallel to it,
Therefore,
So now the resistance of circuit is 2.5 + 0.5 = 3 Ω
(iv) Current drawn I =
Substituting the values we get,
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